Torque stabilization for a rig mast

ABSTRACT

A rig mast torque stabilization system has a racking board extending rearward from a middle portion of a vertical mast. Right and left braces are movable from a transport position to an operating position extending laterally outward from the mast. Right and left mast tethers are each connected to the corresponding brace, and to the mast above the brace. Right and left board tethers are each connected to the corresponding brace, and to the racking board. Right and left vehicle tethers are each connected to the corresponding brace, and to a forward location on the vehicle supporting the mast. The mast tethers, board tethers, and vehicle tethers are configured to be in tension when the racking board is in the board operating position, the mast is in the mast operating position, and the braces are in the brace operating position.

RELATED APPLICATIONS

This Application claims the benefit of Canadian Application No.2,881,002, filed Feb. 3, 2015, said prior application being hereby fullyincorporated by reference herein.

TECHNICAL FIELD

This disclosure relates to the field of well drilling and servicing rigsand in particular a system for resisting torque forces on the mast ofsuch rigs.

BACKGROUND

A typical rig for drilling and servicing wells, such as oil and gaswells, comprises a mast mounted on a transport vehicle for movement fromone work site to another. The mast typically has a winch mechanism atthe top thereof for drawing tubing out of a well. The mast is laid downhorizontally on the vehicle for transport, and moved to a verticalposition at the work site, typically by tipping the front end of themast up so the mast extends upward from the rear end of the vehicle.

Typically as well the mast is extended vertically when at the well site,since a taller mast allows for multiple lengths of tubing to be handledwhich reduces the time required for the various drilling or servicingoperations which require the tubing to be pulled out of the well orplaced in the well. A common configuration is for the mast to comprisetwo or more frame members that telescope up and down to extend andretract the mast. The lengths of tubing are commonly supportedvertically by a racking board which extends rearward from the mast at amiddle vertical location on the mast.

Examples of such rigs are disclosed in U.S. Pat. No. 7,246,983 to Zahnet al. and U.S. Pat. No. 4,290,495 to Elliston.

A significant surface area is presented to wind loading when the rackingboard is filled with tubing extending rearward from the mast. A windpushing laterally on the tubing puts a considerable torque force on themast and causes same to twist. The upper ends of the tubing may movelaterally in response to the wind forces causing them to lean againstthe racking board and add further torque forces on the mast. Thesetorque forces must be resisted to avoid damage to the mast. Typicallyexternal guy wires are attached from the mast and/or racking board toanchors spread across the ground, however these interfere withactivities taking place around the work site. It is also known toprovide internally guyed rigs, typically with outriggers at the rear endof the transport vehicle which extend laterally to stabilize the vehicleand mast, and with the guy wires anchored to the outriggers and to thevehicle itself as well with no actual anchors on the ground.

SUMMARY

The present disclosure provides a system for resisting torque forces onthe racking board of a rig mast that overcomes problems in the priorart.

The present disclosure provides a rig mast torque stabilization systemcomprising a mast pivotally mounted on a vehicle for transport, the mastmovable from a substantially horizontal mast transport position to asubstantially vertical mast operating position extending upward from arear end of the vehicle. A racking board extends, when in a boardoperating position, rearward from a vertical location in a middleportion of the mast when the mast is in the mast operating position.Right and left elongated braces are movably attached to correspondingright and left sides of the middle portion of the mast, and are movablefrom a brace transport position where outer ends of the braces are inproximity to the mast, to a brace operating position where the bracesextend laterally outward from corresponding right and left sides of themast to the outer ends of the braces. Right and left mast tethers areeach connected at a lower end thereof to the corresponding right andleft brace, and each is connected at an upper end thereof to the mast ata location above the corresponding right and left brace. The masttethers are configured to be in tension when the racking board is in theboard operating position, the mast is in the mast operating position,and the braces are in the brace operating position. Right and left boardtethers are each connected at an outer end thereof to an outer end ofthe corresponding right and left brace, and each is connected at aninner end thereof to the racking board. The board tethers are configuredto be in tension when the racking board is in the board operatingposition, the mast is in the mast operating position, and the braces arein the brace operating position. Right and left vehicle tethers are eachconnected at an upper end thereof to the corresponding right and leftbrace, and connected at a lower end thereof to a forward location on thevehicle. The vehicle tethers are configured to be in tension when theracking board is in the board operating position, the mast is in themast operating position, and the braces are in the brace operatingposition.

The tethers, braces, etc. will be sized and connected at locationssuitable for a particular rig configuration. The tension on the boardtethers exerts lateral right and left forces on the racking board thatresists torque forces caused by wind, leaning tubing, or the like.Positioning the braces just below the racking board provides a largeproportion of the tension force in the board tethers providing lateralforce on the racking board with little downward force exerted on theracking board. The system can be configured for a variety of rigconfigurations to suitably stabilize the racking board against torqueforces from wind, leaning tubing and like factors

The above summary is not intended to describe each illustratedembodiment or every implementation of the subject matter hereof. Thefigures and the detailed description that follow more particularlyexemplify various embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

Subject matter hereof may be more completely understood in considerationof the following detailed description of various embodiments inconnection with the accompanying figures, in which:

While the invention is claimed in the concluding portions hereof,preferred embodiments are provided in the accompanying detaileddescription which may be best understood in conjunction with theaccompanying diagrams where like parts in each of the several diagramsare labeled with like numbers, and where:

FIG. 1 is a schematic top view of an embodiment of the rig maststabilization system of the present disclosure in the operatingposition;

FIG. 2 is a schematic side view of the embodiment of FIG. 1 in theoperating position;

FIG. 3 is a schematic top view of the embodiment of FIG. 1 in thetransport position;

FIG. 4 is a schematic side view of the embodiment of FIG. 1 in theoperating position;

FIG. 5 is a schematic side view of the embodiment of FIG. 1 in anintermediate position with the mast vertical but not yet extended;

FIG. 6 is a schematic side view of the embodiment of FIG. 1 in theoperating position with the mast fully extended and all tethers intension;

FIG. 7 is a schematic side view of an internally guyed rig of the priorart;

FIG. 8 is a rear view of the prior art internally guyed rig of FIG. 7;

FIG. 9 is a schematic perspective view of the outer end of the brace ofthe embodiment of FIG. 1;

FIG. 10 is a schematic end view of the outer end of the braceillustrated in FIG. 9;

FIG. 11 is a schematic front view of the braces of the embodiment ofFIG. 1 showing the braces pivoting from the brace transport position tothe brace operating position;

FIG. 12 is a schematic front view of an alternate arrangement of bracesof showing the braces telescoping from the brace transport position tothe brace operating position.

While various embodiments are amenable to various modifications andalternative forms, specifics thereof have been shown by way of examplein the drawings and will be described in detail. It should beunderstood, however, that the intention is not to limit the claimedinventions to the particular embodiments described. On the contrary, theintention is to cover all modifications, equivalents, and alternativesfalling within the spirit and scope of the subject matter as defined bythe claims.

DETAILED DESCRIPTION OF THE DRAWINGS

FIGS. 1-6 schematically illustrate an embodiment of a rig maststabilization system 1 of the present disclosure. The system 1 comprisesa mast 3 pivotally mounted on a vehicle 5 for transport. The mast 3 ismovable from a substantially horizontal mast transport position shown inFIGS. 3 and 4 to a substantially vertical mast operating position shownin FIG. 2 extending upward from a rear end of the vehicle 5. In theillustrated system 1 the mast pivots about a horizontal mast pivot axisMPA to move between horizontal to vertical. Typically such masts operateslightly off exact vertical by about three to four degrees.

A racking board 7 extends, when in a board operating position, rearwardfrom a vertical location in a middle portion of the mast 3 when the mast3 is in the mast operating position shown in FIG. 2.

Right and left elongated braces 9R, 9L are movably attached tocorresponding right and left sides of the middle portion of the mast 3.The braces 9 are movable from a brace transport position 9A where outerends 11 of the braces 9 are in proximity to the mast 3 as shown in FIG.3, to a brace operating position 9B where the braces 9 extend laterallyoutward from corresponding right and left sides of the mast 3 to theouter ends 11 of the braces 9.

Right and left mast tethers 13R, 13L are each connected at a lower endthereof to the corresponding right and left brace 9R, 9L, and each masttether 13 is connected at an upper end thereof to the mast 3 at alocation above the corresponding right and left brace 9. The masttethers 13 are configured to be in tension when, as shown in FIG. 2, theracking board 7 is in the board operating position, the mast 3 is in themast operating position, and the braces 9 are in the brace operatingposition. The mast tethers 13 will typically be connected to the braces9 at or near the outer ends 11 thereof.

Right and left board tethers 15R, 15L are each connected at an outer endthereof to the outer end 11 of the corresponding right and left brace9R, 9L, and each board tether 15 is connected at an inner end thereof tothe racking board 7, and for best advantage to the outer corners of theracking board 7. Like the mast tethers 13, the board tethers 15 areconfigured to be in tension when, as shown in FIG. 2, the racking board7 is in the board operating position, the mast 3 is in the mastoperating position, and the braces 9 are in the brace operatingposition.

Finally, right and left vehicle tethers 17R, 17L are each connected atan upper end thereof to the corresponding right and left brace 9R, 9L,typically at or near the outer ends 11 thereof, and each vehicle tether17 is connected at a lower end thereof to a forward location 19 on thevehicle 5. Like the mast tethers 13 and the board tethers 15, thevehicle tethers 17 are configured to be in tension when, as shown inFIG. 2, the racking board 7 is in the board operating position, the mast3 is in the mast operating position, and the braces 9 are in the braceoperating position.

Further cables and lines extend between the mast 3, the vehicle 5, andthe racking board 7 as is known in the art and are not furtherillustrated to allow clear illustration of the present rig maststabilization system 1.

With all the tethers 13, 15, 17 in tension, it can be seen that lateralright and left stabilizing forces RFR and RFL are exerted on the rackingboard 7. These forces stabilize the mast 3 by resisting lateral forcesfrom wind, tubing leaning on the racking board, and the like which tendto twist the mast 3. The forces RFR, RFL are equal to the right and leftcomponents of the tension forces BF exerted on the board tethers 15. Itcan be seen that as the length of the braces 9 increases, the angle Nincreases as well and the lateral component of the tension force F,which provides the racking board forces RFR, RFL, increases as well.Typically in the present system 1 the length of the braces 9 is selectedto provide sufficient lateral right and left forces RFR and RFL on theracking board 7 while still being practical to use.

In the prior art, rigs are stabilized by external guy wires where guywires connect ground anchors to the racking board however these groundanchors interfere with the work area on the ground around the rig and soare undesirable. Internally guyed systems are also known, for example asschematically illustrated in the system 101 in FIGS. 7 and 8, where guywires 117 connect the racking board 107 with outriggers 121 which extendoutward from the transporting vehicle 105. It can be seen that, becauseof the limited length of the outriggers 121, the angle N′ between theguy wires 117 and the mast 103, which provides the lateral forcecomponent RF′ on the racking board 107, is quite small compared to theangle N in the system 1 of the present disclosure.

Thus in the internally guyed systems of the prior art the lateralcomponent RF′ of the tension force F′ is a small proportion of thetotal, and so a significantly greater tension force F′ must be exertedto achieve a satisfactory stabilizing lateral force RF on the rackingboard 107. It can be seen as well that the downward component of forceDF′ pulling down on the outer end of the racking board 107 is verysignificant, requiring further guy wires extending up to the upper partof the mast 103 and from the mast 103 to the vehicle 105.

In contrast it can be seen in FIG. 2 that the downward component DF ofthe tension force BF in the board tether 15 is a small proportion of thetotal.

As is common with service and drilling rigs of the type contemplated themast 3 is extendable. As schematically illustrated in FIGS. 3-6, themast 3 is retracted when in the mast transport position seen in FIGS. 3and 4, and when moving from the mast transport position to the mastoperating position the mast 3 is moved from the horizontal transportposition of FIG. 4 to a vertical retracted position shown in FIG. 5 witha lower mast section 3A extending upward from the rear end of thevehicle 5, and then an upper mast section 3B is moved upward withrespect to the lower mast section 3A to extend the mast 3 vertically tothe mast operating position shown in FIG. 6. The braces 9 are attachedto an upper portion of the lower mast section 3A and the racking board 7is attached to a lower portion of the upper mast section 3B, such thatthe racking board 7 moves upward with the upper mast section 3B to avertical position in proximity to the braces 9 when the mast 3 moves tothe mast operating position.

The tethers 13, 15, 17 can be installed and tensioned after the mast 3,racking board 7, and braces 9 are in their operating positions, and thismay be most convenient where the mast is of a fixed length and notextendable. Where as is common the industry, the mast is extendable,installing the tethers and tensioning them can be more problematic.

The illustrated system 1 with the extendable mast 3 convenientlyfacilitates installation and tensioning of the tethers by using rightand left main tethers 23R, 23L to provide the corresponding right andleft board tethers 15R, 15L and right and left vehicle tethers 17R, 17L.Each main tether 23 comprises a board section 23A between the upper endthereof connected to the racking board 7 and a stop member 25 attachedto the main tether 23 at a distance from the racking board 7 thatcorresponds to a length of the board tether 15, and a vehicle section23B between the stop member 25 and the lower end thereof attached to theforward location on the vehicle which corresponds to the length of thevehicle tether 17.

The vehicle section 23B of each main tether 23 passes through a hole 27in a stop plate 29 attached to the outer end 11 of the correspondingbrace 9 and then over a pulley 31 attached to the corresponding brace 9,and then downward and forward to the forward location 19 on the vehicle.

As is common in the art, the racking board 7 is pivotally attached tothe upper mast section 3B about a horizontal board pivot axis BPA andthe racking board 7 pivots upward to a board transport position lyingagainst the upper mast section 3B as seen in FIGS. 3 and 4, and thenpivots downward to the board operating position extending rearward fromthe mast as shown in FIGS. 5 and 6 when the mast 3 is moved from thehorizontal transport position of FIG. 4 to the vertical position of FIG.5.

In operation, when moving the system 1 from a transport position to anoperating position the braces 9 are moved from the transport position 9Ashown in phantom lines in FIG. 3 lying against the lower mast section 3Aout to the board operating position . When the mast 3 and racking board7 are in their transport positions as shown in FIGS. 3 and 4, and whenthe mast 3 is moved to the vertical position and the racking board 7moves to the board operating position as shown in FIG. 5, the vehiclesection 23B of each main tether 23 is loose, as shown with the lower endthereof lying coiled on the ground in FIG. 4 and coiled lying on thevehicle 5 in FIG. 5.

The lower end of the main tether 23 is pulled downward as the upper mastsection 3B, and the racking board 7 and board section 23A of the maintether 23 attached thereto, moves upward, and when the mast 3 is in themast operating position of FIG. 6 the lower end of the main tether 23 isconnected to a tensioning device 33 at the forward location on thevehicle 19. The tensioning device 33, such as a winch, turnbuckle, orthe like is operative to exert tension on the main tether 23 such thatthe stop members 25 on the right and left main tethers 23R, 23L bearagainst the stop plates 29 on the corresponding right and left bracesand exert a forward force on the stop plates 29. The stop members 25 islocated on the main tethers 23 at locations such that when the stopmember 25 contacts the stop plate 29, the board section 23A of the maintether 23 is in tension. The mast tethers 13 have a length selected suchthat the downward force exerted by the tension in the vehicle section23B of the main tether 23 exerts tension in the mast tethers 13.

The combination of forces FM, FB, and FV exerted by the mast tether 13,board tether 17, 23A, and vehicle tether 17, 23B on the outer end 11 ofthe brace 9 result in a force B on the brace 9 that is generally inwardtoward the mast 3.

Typically the stop member 25 is releasably clamped to the main tether 23with a clamp device 35 so that its location on the main tether can beadjusted to conveniently set up the system initially, and to adjust theposition to compensate for stretch or like variations during continueduse.

For most applications it is contemplated that the outer ends 11 of thebraces 9 will be just slightly below the board pivot axis BPA when theracking board 7 is in the board operating position, the mast 3 is in themast operating position, and the braces 9 are in the brace operatingposition. This results in a small downward force component DF as shownin FIG. 2, which prevents the racking board 7 from moving upward, andyet keeps a large proportion of the force FB acting perpendicular to theracking board 7 to maximize the lateral stabilizing forces RFR, RFL.

In the illustrated system 1 the right and left braces 9R, 9L arepivotally attached to corresponding right and left sides of the mast 3,and pivot from the brace transport position 9A folded substantially intoalignment with the mast 3, to the brace operating position 9B extendingsubstantially perpendicularly outward from the mast 3, as schematicallyillustrated in FIG. 11.

It is also contemplated that the braces could be movably attached inother ways, for example FIG. 12 schematically illustrates the braces 9′telescopically attached to corresponding right and left sides of themast 3′, where the braces 9′ telescope outward from the brace transportposition 9B′ to the brace operating position 9A′.

The tethers will typically be wire cable, but could also be chain or thelike if same suited a particular application. The exact configuration ofthe system, such as dimensions, attachment locations of the tethers,braces, etc. will depend on the particular rig in question, and furtherstabilization equipment such as outriggers or the like will typically berequired to support the mast vertically, however the tethers and bracesdescribed herein can be configured for a variety of rig configurationsto suitably stabilize the racking board against torque forces from wind,leaning tubing and like factors.

The foregoing is considered as illustrative only of the principles ofthe invention. Further, since numerous changes and modifications willreadily occur to those skilled in the art, it is not desired to limitthe invention to the exact construction and operation shown anddescribed, and accordingly, all such suitable changes or modificationsin structure or operation which may be resorted to are intended to fallwithin the scope of the claimed invention.

Various embodiments of systems, devices, and methods have been describedherein. These embodiments are given only by way of example and are notintended to limit the scope of the claimed inventions. It should beappreciated, moreover, that the various features of the embodiments thathave been described may be combined in various ways to produce numerousadditional embodiments. Moreover, while various materials, dimensions,shapes, configurations and locations, etc. have been described for usewith disclosed embodiments, others besides those disclosed may beutilized without exceeding the scope of the claimed inventions.

Persons of ordinary skill in the relevant arts will recognize that thesubject matter hereof may comprise fewer features than illustrated inany individual embodiment described above. The embodiments describedherein are not meant to be an exhaustive presentation of the ways inwhich the various features of the subject matter hereof may be combined.Accordingly, the embodiments are not mutually exclusive combinations offeatures; rather, the various embodiments can comprise a combination ofdifferent individual features selected from different individualembodiments, as understood by persons of ordinary skill in the art.Moreover, elements described with respect to one embodiment can beimplemented in other embodiments even when not described in suchembodiments unless otherwise noted.

Although a dependent claim may refer in the claims to a specificcombination with one or more other claims, other embodiments can alsoinclude a combination of the dependent claim with the subject matter ofeach other dependent claim or a combination of one or more features withother dependent or independent claims. Such combinations are proposedherein unless it is stated that a specific combination is not intended.

Any incorporation by reference of documents above is limited such thatno subject matter is incorporated that is contrary to the explicitdisclosure herein. Any incorporation by reference of documents above isfurther limited such that no claims included in the documents areincorporated by reference herein. Any incorporation by reference ofdocuments above is yet further limited such that any definitionsprovided in the documents are not incorporated by reference hereinunless expressly included herein.

For purposes of interpreting the claims, it is expressly intended thatthe provisions of 35 U.S.C. §112(f) are not to be invoked unless thespecific terms “means for” or “step for” are recited in a claim.

1. A rig mast torque stabilization system comprising: a mast pivotallymounted on a vehicle for transport, the mast movable from asubstantially horizontal mast transport position to a substantiallyvertical mast operating position extending upward from a rear end of thevehicle; a racking board extending, when in a board operating position,rearward from a vertical location in a middle portion of the mast whenthe mast is in the mast operating position; right and left elongatedbraces movably attached to corresponding right and left sides of themiddle portion of the mast, the braces movable from a brace transportposition where outer ends of the braces are in proximity to the mast, toa brace operating position where the braces extend laterally outwardfrom corresponding right and left sides of the mast to the outer ends ofthe braces; right and left mast tethers, each mast tether connected at alower end thereof to the corresponding right and left brace, and eachmast tether connected at an upper end thereof to the mast at a locationabove the corresponding right and left brace, the mast tethersconfigured to be in tension when the racking board is in the boardoperating position, the mast is in the mast operating position, and thebraces are in the brace operating position; right and left boardtethers, each board tether connected at an outer end thereof to an outerend of the corresponding right and left brace, and each board tetherconnected at an inner end thereof to the racking board, the boardtethers configured to be in tension when the racking board is in theboard operating position, the mast is in the mast operating position,and the braces are in the brace operating position; right and leftvehicle tethers, each vehicle tether connected at an upper end thereofto the corresponding right and left brace, and each vehicle tetherconnected at a lower end thereof to a forward location on the vehicle,the vehicle tethers configured to be in tension when the racking boardis in the board operating position, the mast is in the mast operatingposition, and the braces are in the brace operating position.
 2. Thesystem of claim 1 wherein the mast is extendable, and wherein the mastis retracted when in the mast transport position, and wherein whenmoving from the mast transport position to the mast operating positionthe mast is moved from the horizontal transport position to a verticalretracted position with a lower mast section extending upward from therear end of the vehicle, and then an upper mast section is moved upwardwith respect to the lower mast section to extend the mast vertically tothe mast operating position.
 3. The system of claim 2 wherein the bracesare attached to an upper portion of the lower mast section and theracking board is attached to a lower portion of the upper mast section,such that the racking board moves upward with the upper mast section toa vertical position in proximity to the braces when the mast moves tothe mast operating position.
 4. The system of claim 3 wherein the rightand left board tethers and right and left vehicle tethers are providedby corresponding right and left main tethers, each main tethercomprising a board section between an upper end thereof connected to theracking board and a stop member attached to the main tether at adistance from the racking board that corresponds to a length of theboard tether, and a vehicle section between the stop member and a lowerend thereof attached to the forward location on the vehicle.
 5. Thesystem of claim 4 wherein the vehicle section of each main tether passesthrough a hole in a stop plate attached to the outer end of thecorresponding brace and then over a pulley attached to the correspondingbrace, and then downward and forward to the forward location on thevehicle, where in operation the lower end of the main tether is pulleddownward as the upper mast section moves upward, and when the mast is inthe mast operating position the lower end of the main tether isconnected to a tensioning device operative to exert tension on the maintether such that the stop members on the right and left main tethersbear against the stop plates on the corresponding right and left bracesand exert a forward force on the stop plates.
 6. The system of claim 4wherein the stop member is releasably clamped to the main tether.
 7. Thesystem of claim 5 wherein the racking board is pivotally attached to theupper mast section about a substantially horizontal board pivot axis andwherein the racking board pivots upward to a board transport positionlying against the upper mast section, and downward to the boardoperating position extending rearward from the mast.
 8. The system ofclaim 7 wherein the outer ends of the braces are below the board pivotaxis when the racking board is in the board operating position, the mastis in the mast operating position, and the braces are in the braceoperating position.
 9. The system of claim 8 wherein the right and leftbraces are pivotally attached to corresponding right and left sides ofthe mast, and pivot from the transport position folded substantiallyinto alignment with the mast, to the operating position extendingsubstantially perpendicularly outward from the mast.
 10. The system ofclaim 1 wherein the right and left braces are telescopically attached tocorresponding right and left sides of the mast, and telescope outwardfrom the brace transport position to the brace operating position.